This prospective, multiple cohort, longitudinal study of the etiology of alcoholism has as its objective the elucidation of those antecedent factors in the individual which confer an increased risk of developing alcohol problems. Since we believe it likely that addiction to alcohol, and to other drugs, results from an intermingling of constitutional and environmental influences, our assessment of individuals employs measures from a variety of disciplines (e.g. sociology, psychology, physiology, biochemistry) to characterize our subject population. Now in its third year, the study completed intake of the first wave of 475 adolescents in February 1980, equally divided as to sex and as to birth cohorts of 1961, 1964 and 1967, and has more than half completed the second wave of participants of birth years 1962, 1965, and 1968. In about April of 1982, Wave 1 will be retested, as will other Waves at 3-year intervals to age 24, and thereafter at 6-years intervals. The data base consists of about 5,000 items per subject and is now in the preliminary stages of statistical and other analysis; because initial intakes are of different ages, we shall also be able to provide cross sectional analyses of the data. We expect that our results in the near future will be useful in strategies of prevention and in the guidance of public policy relating to alcohol and drug use.